JPH0649790B2 - Opaque stretched molded article and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention relates to a stretch-molded article containing a polypropylene resin as a main component. More specifically, a composition obtained by adding a specific petroleum hydrocarbon resin and an inorganic filler to crystalline polypropylene was stretched to generate a large number of fine voids inside or on the surface of the molded article, and imparted with an opaque or pearly feeling. The present invention relates to a stretched molded product and a method for producing the same.

[Conventional technology]

Generally, a molded article having a pearly feeling or an opaque feeling is used, for example, as a uniaxially or biaxially stretched film in general packaging materials, decorative materials, synthetic papers, calligraphic printing papers, and the like.
It is also widely used as a tape, ribbon or filament for packing materials, woven yarns and the like.

Conventionally, as a method for making a molded article pearlized or opaque, (1) a method of adding a glossy substance such as a white pigment, an extender pigment or pearl essence, (2) a foaming agent is added at the time of molding to generate a large number of bubbles. Forming method, (3) JP-A-63-24
A method of adding a large amount of an inorganic filler as described in JP-A No. 532, JP-A-63-117043, and the like, followed by stretching to form voids. (4) Treating the molded product with a solvent or chemicals A method of dulling and (5) a method of dispersing a high melting point polymer such as nylon and polyester in polypropylene (U.S. Pat. No. 4,377,616, JP-A-61-157547) are known.

However, these methods have the following drawbacks. That is, regarding (1), it is necessary to use different pigments for opacification and pearlization, and pearl essence is also very expensive. In addition, a mixing method and apparatus that take into consideration the dispersion of these pigments are required. For (2), molding conditions,
It is necessary to select a foaming agent depending on the application, and it is difficult to obtain uniform fine foaming with a thin film such as a film.

Regarding (3), it is easy to make opaque by adding a large amount of inorganic filler, but the fluidity during extrusion is significantly reduced, the screen pack is clogged, and moisture absorption due to the inorganic filler is caused.・ There are many troubles during production, such as foaming and poor dispersion, and it takes a long time to replace the resin. Only the product obtained has a reduced glossiness or a roughened surface. . Further, there are drawbacks such as poor impact resistance.
In addition, (4) is performed in a post-treatment process and requires a process for removing solvents and chemicals, which is disadvantageous in terms of equipment and cost. Also, the product has a pearly feeling although a dull feeling is obtained. There is a problem that can not be obtained. In addition, a method of stretching a compound obtained by adding an incompatible polymer such as nylon or polyester to polypropylene of (5) to make it opaque (US Patent No.
No. 4,377,616) nylon and polyester have poor compatibility with polypropylene and have very different fluidity, making uniform dispersion difficult, resulting in poor stable productivity and difficulty in obtaining a uniform opaque film in a stable manner. .

[Problems to be Solved by the Invention]

The object of the present invention is to solve the problems of the conventional opacifying film, to have an improved opacity and pearly feeling, to be lightweight and to have good gas barrier properties, and to be opaque by blending a small amount of an inorganic filler. The object of the present invention is to provide a uniform opaque film with less stable productivity and a method for producing the same, which is capable of achieving high efficiency, has no disadvantages in terms of production troubles, equipment and costs.

[Means for Solving the Problems]

As a result of various studies on the productivity of the method (3) most useful for opacification and the gloss improvement of the product, the present inventors have used a cyclopentadiene-based petroleum resin having a specific softening point and an inorganic filler in combination. By using the added composition, it has improved opacity, pearly feeling, etc., and is lighter and has better gas barrier properties than the case of using a composition in which only an inorganic filler is mixed with polypropylene. The present inventors have found that various molded products can be obtained, opacity can be achieved by adding a small amount of an inorganic filler, and productivity is extremely excellent, and the present invention has been achieved.

That is, the present invention includes: (1) 0.1 to 20 parts by weight of an inorganic filler powder and 100 to 100 parts by weight of crystalline polypropylene, and a cyclopentadiene-based petroleum resin 3 having a softening point (ring and ball method) of 160 ° C. or higher.
It is composed of a composition containing 40 parts by weight, has a large number of fine cavities, and has a total light transmittance of 50% or less and a density of 0.
An opaque stretch-molded product having a weight of 8 g / cm ³ or less, (2) 0.1 to 20 parts by weight of inorganic filler powder and hydrogenation at a softening point (ring and ball method) of 160 ° C. or more based on 100 parts by weight of crystalline polypropylene. A composition prepared by blending 3 to 40 parts by weight of a cyclopentadiene-based petroleum resin was prepared at 10 ° C from the crystalline melting point of the crystalline polypropylene and the softening point of the petroleum resin.
After melt-extruding at a higher temperature and cooling to prepare an unstretched raw fabric, it is stretched at least twice in at least one direction at a temperature lower than the melting point of the polypropylene and the softening point of the petroleum resin to form many fine cavities. (3) Softening point (ring and ball method) obtained by hydrogenating a petroleum resin containing 50% by weight or more of a cyclopentadiene component.
An opaque stretched molded article according to (1) above, which uses a hydrogenated cyclopentadiene-based petroleum resin having a iodine value of 20 or less at 70 to 200 ° C. (4) Hydrogen petroleum resin containing 50% by weight or more of a cyclopentadiene component Softening point (ring and ball method) 1
The method for producing an opaque stretched molded article according to (2) above, which comprises using a hydrogenated cyclopentadiene-based petroleum resin having a iodine value of 20 or less at 70 to 200 ° C.

(5) An opaque stretched molded article according to the above (2), characterized in that a composition containing 1 to 10 parts by weight of calcium carbonate or / and talc having an average particle diameter of 10 μm or less is used as the inorganic filler. (6) A composition containing 0.1 to 2.0 parts by weight of silica or / and a silicate having an average particle size of 10 μ or less is used as the inorganic filler, (2) The present invention relates to the method for producing an opaque stretch-molded product described above.

The crystalline polypropylene used in the present invention is a homopolymer of propylene, a copolymer containing propylene as a main component with ethylene or / and another α-olefin, or a mixture thereof.

The inorganic filler used in the present invention is calcium carbonate, talc, clay, kaolin, silica, diatomaceous earth, magnesium carbonate, barium carbonate, magnesium sulfate, barium sulfate, calcium sulfate, aluminum hydroxide, magnesium hydroxide, alumina, mica, glass. Powders, shirasu balloons, zeolites, hydrotalcites, titanium oxides, oxides of metals such as aluminum oxide, and the like can be used various inorganic fillers known to be used for porosification of polyolefins by stretching, and among them, the average Calcium carbonate, talc, clay, silica or silicate having a particle size of 10 μm or less is particularly preferable. If this average particle size is too large, troubles are likely to occur during production, and the obtained product also has a roughened surface and the surface gloss is significantly reduced.

In addition, you may use these inorganic fillers in mixture of several types. Further, it is also possible to use those obtained by surface-treating these fillers with known substances such as fatty acids or metal salts thereof, silane coupling agents and the like.

The cyclopentadiene-based petroleum resin used in the present invention is a cyclopentadiene obtained from steam cracking of petroleum naphtha or the like, dicyclopentadiene and a multimer thereof or an alkyl-substituted fraction thereof or a mixture thereof as a main component. In the presence or absence of a solvent, under an atmosphere of an inert gas such as nitrogen gas, preferably at a temperature of 220 to 320 ° C., under a pressure at which the polymerization system can be maintained in a liquid phase, for several hours or more. A high molecular weight / high softening point cyclopentadiene-based petroleum resin containing 50 wt% or more of a cyclopentadiene-based component obtained by thermal polymerization, and a conventionally known method for producing the petroleum resin, that is, a metal such as palladium, nickel or cobalt, or Using a catalyst such as the oxide, in the presence of a solvent, a temperature of 150 to 300 ° C., a temperature of 10 to 15
It is a hydrogenated cyclopentadiene-based petroleum resin or a mixture thereof hydrogenated under a hydrogen pressure of 0 kg / cm ² .
The cyclopentadiene fraction may be polymerized in one step, but it may be polymerized in two or more steps, for example, dicyclopentadiene is polymerized in two steps. The polymerization step, the polymerization and the hydrogenation step may be continuous or batch type. Any of

Among the cyclopentadiene-based petroleum resins thus obtained, their softening point (ring and ball method) is 160 in the present invention.
Must be above ℃. If the softening point does not reach 160 ° C, both the opaqueness and the pearly feeling are insufficient, and the stretch-molded article aimed at by the present invention cannot be obtained.
As in JP-A-61-203140 and conventionally known hydrogenated petroleum resins, the direction is completely opposite to that of the present invention, that is, the molded product is transparent and contains opaque and minute cavities for the purpose of the present invention. However, it is impossible to obtain a stretch-molded product having a very characteristic property such as having a pearly luster.

In the present invention, a hydrogenated cyclopentadiene-based petroleum resin having a softening point of 160 ° C. or higher is preferable, and a softening point of 170 to
Hydrogenated cyclopentadiene-based petroleum resin having an average molecular weight of 1200 or more and an iodine value of 20 or less measured at 200 ° C. by a gel permeation chromatography method has excellent compatibility with polypropylene and dispersibility with an inorganic filler. Also good, stable processing, and whiteness
A stretched molded article having excellent opacity is obtained, which is particularly preferable.
Compared with high melting point polymers such as nylon and saturated polyester resins, this hydrogenated cyclopentadiene resin has excellent compatibility with crystalline polypropylene and can be uniformly dispersed. A molded product having excellent properties and a high gloss is obtained, and a uniform product can be obtained.

The composition used in the present invention contains, in 100 parts by weight of polypropylene, 0.1 to 20 parts by weight of an inorganic filler powder and 3 to 40 parts by weight of a cyclopentadiene-based petroleum resin having a softening point (ring and ball method) of 160 ° C. or higher. . If the added amount of the inorganic filler is less than 0.1 part by weight, the light transmittance is large and the opacity is insufficient, and if it exceeds 20 parts by weight, problems such as clogging during film production, poor dispersion and stretch breakage are likely to occur, The obtained film is also unfavorable because the surface gloss and the pearly feeling are reduced. If the amount of the petroleum resin added is less than 3 parts by weight, the effect of imparting opacity, which is the object of the present invention, is insufficient, and if it exceeds 40 parts by weight, extrusion unevenness and stretch breakage tend to occur during molding, resulting in extremely high productivity. Is not preferable.

By stretching the composition in which the inorganic filler and a specific cyclopentadiene-based petroleum resin are added together in a specific range, a stretched product having extremely excellent opacity and high surface gloss can be obtained, and particularly preferably. , 1 to 10 parts by weight of calcium carbonate or talc having an average particle size of 10 μ or less, and a softening point of 17 per 100 parts by weight of polypropylene.
Hydrogenated cyclopentadiene-based petroleum resin at 0 to 200 ° C 5
~ 30 parts by weight added composition, or average particle size 10μ
The following silica or zeolite is biaxially stretched simultaneously or sequentially using a composition to which 0.1 to 2 parts by weight and 5 to 30 parts by weight of a hydrogenated cyclopentadiene-based petroleum resin having a softening point of 170 to 200 ° C. are added, or A combination of these is particularly preferable.

In the composition of the polypropylene used in the present invention and the inorganic filler and the cyclopentadiene-based petroleum resin, if necessary, various additives known to be added to polypropylene, such as known phenol-based or phosphorus-based or thioether A processing stabilizer / antioxidant such as a system, a lubricant / slip agent such as a metal salt of a higher fatty acid or a fatty acid amide, an antistatic agent, a pigment and various polymers may be added.

This composition can be easily obtained by mixing a predetermined blend with an ordinary blender, a mixer or the like, and the crystalline melting point of the crystalline polypropylene and the cyclopentadiene-based resin using an extruder, a Banbury mixer or the like. From the viewpoint of use, it is particularly preferable that the composition is pelletized by melt-mixing at a temperature higher than the softening point by 10 ° C. Also, for polypropylene or other resins, an inorganic filler or /
It is also useful to add a large amount to the petroleum resin, masterbatch each of them alone or in combination, and prepare a mixed composition with polypropylene.

The composition thus obtained, after forming an unstretched raw fabric with a melt extruder, by uniaxially or biaxially stretched by a known method, a film, a sheet, a yarn, a filament,
An opaque stretch-molded article intended for the present invention such as a hollow container can be obtained. In this case, the melt extrusion is preferably performed at a temperature higher than the crystal melting point of the crystalline polypropylene in the composition and the softening point of the petroleum resin by 10 ° C. or more. Is formed, and this original fabric is uniaxially or biaxially stretched. This stretching method may be any known method such as roll stretching, oven stretching, hot plate stretching or the like known uniaxial stretching method or tubular stretching, tenter method stretching or the like simultaneous or sequential biaxial stretching, etc., It is necessary to set the raw fabric temperature at the time of stretching to a temperature lower than the softening points of the crystalline polypropylene and the petroleum resin in the composition to be used. By selecting this condition, the total light transmittance is 50% or less. It is also possible to easily obtain an opaque stretched molded product having a density of 0.8 g / cm ³ or less.

In the case of stretching in an oven, the hot air temperature may be set above the melting point of polypropylene, but it is not possible to stretch and orient polypropylene above the melting point. This is because the actual temperature of the drawn raw fabric has not reached the melting point due to the relationship between the thickness of the
In the present invention, the actual temperature of the original stretched fabric is referred to as the stretching temperature.

A stretched molded article aimed at by the present invention can be obtained by stretching at least 2 times in at least one direction at a temperature lower than the melting point of polypropylene used in the composition and at a temperature not higher than the softening point of the petroleum resin, but the area is 4 times or more. Is preferable, and simultaneous or sequential biaxial stretching in which high-area stretching having an area ratio of about 10 to 60 times is particularly preferable.

The present invention also includes a laminate in which the composition of the present invention is used as a core layer, and a layer containing a polypropylene-based resin as a main component is formed on one or both surfaces before or after the stretching, and only the core layer is opaque. To do.

The composition used in the present invention, in the unstretched molded product obtained by molding without stretching, only a white translucent molded product is obtained,
Since the density is higher than that of polypropylene alone, the molded article aimed at by the present invention cannot be obtained, and it can be easily classified according to its appearance, density and the like.

The stretched molded product obtained in the present invention has a total light transmittance of 5
The characteristic is that the density is 0% or less and the density is 0.8 g / cm ³ or less. If the total light transmittance exceeds 50%, the opacity is insufficient and the density is 0.8 g / cm 3. ^If it exceeds ³ , the internal foaming will be insufficient and an opaque and pearly stretch-molded product cannot be obtained. Stretch-molded products having a total light transmittance of 40% or less and a density of 0.75 g / cm ³ or less are particularly preferable because they are excellent in opacity, light-shielding property and pearl luster.

The stretch-molded product obtained in the present invention, if necessary, air,
Surface treatment such as corona treatment and plasma treatment can be performed in an atmosphere of oxygen, nitrogen and the like.

[Examples and comparative examples]

Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples. The method for evaluating the characteristic ground used in the following examples and comparative examples was as follows.

(1). Softening point (ring and ball method): According to JIS 2207. (Unit: ° C) (2). Iodine value; According to JIS K0070-1966.

It refers to the number of grams of iodine added to unsaturated components in 100 g of a sample.

(3). Density: A value obtained by measuring the weight per 1 m ^{2 of the} molded product, converting it per 1 cm ² , and dividing by the thickness cm.

(Unit: g / cm ³ ) (4). Total light transmittance: According to JIS K-6714.

(5). Haze: According to ASTM D1003.

(6) .MFR (melt flow rate): JIS K7210-1776 test condition 14 (230
C., 2.16 kgf). (Unit: g / 10mi
n. (7). Crystal melting point (Tm): About 10 mg using a scanning differential calorimeter (abbreviation: DSC)
The sample was set and measured at room temperature at a temperature rising rate of 20 ° C./minute to measure the endothermic curve associated with melting of the crystal. The peak temperature of the endothermic curve associated with melting was defined as Tm (unit: ° C).
At this time, when a plurality of melting peaks are observed, the one having the maximum peak area is defined as Tm.

(Examples 1 to 8 and Comparative Examples 1 to 4) Crystalline polypropylene powder 1 containing MFR1.5, Tm of 163 ° C., and 94 wt% of an insoluble portion in n-heptane.
To 100 parts by weight of phenolic antioxidant BHT0.
1 part by weight, 0.1 part by weight of calcium stearate, and a predetermined amount of the inorganic filler and / or hydrogenated cyclopentadiene-based petroleum resin shown in Table 1 were added, mixed with a Henschel mixer, and then melted at 240 ° C. through an extruder. The mixture was mixed, cooled and cut to obtain a pelletized composition. Each of the obtained compositions was melt extruded at a temperature of 260 ° C. using an extruder having a diameter of 40 mm and a T-die having a width of 30 cm, and then 45 ° C.
It was rapidly cooled with a mirror-like cooling roll kept at the above temperature to obtain an unstretched raw sheet having a thickness of 1.2 mm. Next, this raw sheet is cut into squares, preheated at a temperature of 155 ° C. for 70 seconds using a pantograph type biaxial stretching machine, and then vertically and horizontally simultaneously 2
The film was stretched by 5.2 times in each direction and heat-treated under tension at the same temperature for 15 seconds to obtain 13 kinds of biaxially stretched films. The characteristic values of the obtained film are also shown in Table 1.

The cyclopentadiene-based petroleum resin was obtained by polymerizing cyclopentadiene or dicyclopentadiene obtained by steam cracking of naphtha by a commonly known method while adjusting the polymerization time, temperature and pressure. Furthermore, hydrogenation is performed at 250 ° C. and 80 ° C. using a nickel-based catalyst.
The one obtained under the hydrogen pressure of kg / cm ² was used.

As is clear from Table 1, the films of Examples 1 to 8 using the composition in which the inorganic filler according to the present invention and the petroleum resin are added within a specific range have high opacity (large haze, The film of Comparative Example 2 in which the light transmittance is small) and the glossiness is high but only the inorganic filler is added has insufficient opacity (small haze, high light transmittance), low glossiness, and the petroleum resin In Comparative Example 4 in which only the additive is added, the total light transmittance is also high and the opacity is insufficient.

Further, as is clear from Comparative Example 3, even if a composition in which a cyclopentadiene-based petroleum resin and an inorganic filler are added together is used and the softening point of the cyclopentadiene-based resin does not reach the range of the present invention, the total light transmittance is It is found that the opacity is less than that of the inorganic filler alone (Comparative Example 2) in which the amount of the inorganic filler is small and the amount thereof is small.

Comparative Example 5 The composition used in Example 1 was melt-extruded at 260 ° C. using a single-screw extruder having a diameter of 65 mmφ and a T-die having an effective width of 60 mm, and a rough surface cooling roll having a diameter of 400 mm kept at 25 ° C. Is cooled with a coil, and wound at a speed of 30 m / min, a width of 400 mm,
An unstretched film having a thickness of 30 μ was obtained. The obtained unstretched film was a transparent type film having a density of 0.90 g / cm ³ , a haze of 8.5%, and a total light transmittance of 84%, although there was a slight cloudiness, but an object could be seen through the film. ,
It can be seen that the unstretched film cannot be made opaque.

Example 9 Phenolic antioxidant Irganox 1010 was added to a crystalline ethylene / propylene random copolymer having an MFR of 2.0, a Tm of 158 ° C. and an ethylene content of 0.4% by weight.
(Manufactured by Ciba-Geigy) 0.2 parts by weight, BHT 0.1 parts by weight, calcium stearate 0.15 parts by weight, 0.4 parts by weight of silica having an average particle size of 3 μ as an inorganic filler, softening point (ring and ball method) 172 ° C., 250 parts by weight of a hydrogenated cyclopentadiene-based petroleum resin containing a molecular weight (GPC method) of 1542 and a cyclopentadiene component of about 60% by weight was added to 250
The composition was melt-kneaded at ℃ and pelletized. The resulting composition was melt extruded at 260 ° C. as in Example 1 and 4
It was rapidly cooled with a 0 ° C. cooling roll to obtain an unstretched original fabric having a thickness of 1.2 mm. The obtained raw fabric was preheated at a temperature of 153 ° C. for 60 seconds using a pantograph-type biaxial stretching device, and then stretched 4.2 times in the flow (longitudinal) direction of the raw fabric, and then immediately orthogonal (transverse). The film was stretched 9 times in the direction and heat-treated at the same temperature while being relaxed by 3% in both directions to obtain a sequentially biaxially stretched film having a thickness of about 40 μm.

The obtained biaxially stretched film was a beautiful film having an opaque and pearly luster with a density of 0.61 g / cm ³ , a haze of 94%, a total light transmittance of 22% and a gloss of 55%.

(Effects of the Invention) Compared with conventionally known methods, the present invention can obtain an opaque stretched molded article with extremely high productivity and at low cost. It can be widely used for general packaging materials, decoration materials, packaging materials, woven yarn, etc. by taking advantage of its properties, light weight and unique pearl luster.

Claims (6)

[Claims] 1. A composition in which 0.1 to 20 parts by weight of an inorganic filler powder and 3 to 40 parts by weight of a cyclopentadiene-based petroleum resin having a softening point (ring and ball method) of 160 ° C. or higher are mixed with 100 parts by weight of crystalline polypropylene. An opaque stretch-molded product which is composed of a plurality of fine voids and has a total light transmittance of 50% or less and a density of 0.8 g / cm ³ or less. 2. An inorganic filler powder of 0.1 to 20 parts by weight and a softening point (ring and ball method) of 3 to 40 parts by weight of a hydrogenated cyclopentadiene-based petroleum resin having a softening point (ring and ball method) of 160 ° C. or more per 100 parts by weight of crystalline polypropylene. The composition prepared above is melt-extruded at a temperature higher than the crystalline melting point of the crystalline polypropylene and the softening point of the petroleum resin by 10 ° C. or more and cooled to prepare an unstretched raw material, and then the melting point of the crystalline polypropylene and the petroleum 2 at least in one direction at temperatures below the softening point of the resin
A method for producing an opaque stretched molded article, which comprises stretching a number of times to generate a large number of fine voids. 3. A hydrogenated cyclopentadiene-based petroleum resin having a softening point (ring and ball method) of 170 to 200 ° C. and an iodine value of 20 or less obtained by hydrogenating a petroleum resin containing 50% by weight or more of a cyclopentadiene component is used. The opaque stretch-molded article according to claim 1. 4. A hydrogenated cyclopentadiene-based petroleum resin having a softening point (ring and ball method) of 170 to 200 ° C. and an iodine value of 20 or less obtained by hydrogenating a petroleum resin containing 50% by weight or more of a cyclopentadiene component. The method for producing an opaque stretched molded article according to claim 2. 5. An opaque stretch-molded article according to claim 2, wherein a composition containing 1 to 10 parts by weight of calcium carbonate or / and talc having an average particle size of 10 μm or less is used as the inorganic filler. Manufacturing method. 6. The opacifying agent according to claim 2, wherein a composition containing 0.1 to 2.0 parts by weight of silica or / and a silicate having an average particle diameter of 10 μm or less is used as the inorganic filler. Of producing the stretched molded product.